From 57787fa42f9fc12fe18938eefc2acb2dc2bde9ae Mon Sep 17 00:00:00 2001 From: Johannes Thumshirn Date: Thu, 25 Apr 2024 05:02:39 -0700 Subject: block: check if zone_wplugs_hash exists in queue_zone_wplugs_show Changhui reported a kernel crash when running this simple shell reproducer: # cd /sys/kernel/debug/block && find . -type f -exec grep -aH . {} \; The above results in a NULL pointer dereference if a device does not have a zone_wplugs_hash allocated. To fix this, return early if we don't have a zone_wplugs_hash. Reported-by: Changhui Zhong Fixes: a98b05b02f0f ("block: Replace zone_wlock debugfs entry with zone_wplugs entry") Signed-off-by: Johannes Thumshirn Reviewed-by: Damien Le Moal Link: https://lore.kernel.org/r/e5fec079dfca448cc21c425cfa5d7b291f5faa67.1714046443.git.johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe --- block/blk-zoned.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'block') diff --git a/block/blk-zoned.c b/block/blk-zoned.c index 3a796420f240..bad68277c0b2 100644 --- a/block/blk-zoned.c +++ b/block/blk-zoned.c @@ -1774,6 +1774,9 @@ int queue_zone_wplugs_show(void *data, struct seq_file *m) unsigned int zwp_bio_list_size, i; unsigned long flags; + if (!disk->zone_wplugs_hash) + return 0; + rcu_read_lock(); for (i = 0; i < disk_zone_wplugs_hash_size(disk); i++) { hlist_for_each_entry_rcu(zwplug, -- cgit v1.2.3